[RFC PATCH 8/9] scripts/get_maintainer.py: add support reading patch files

["Alex Bennée" <alex.bennee@linaro.org>]

Not so different from individual files, we just need to parse the
patch looking for the files and add them to the list. As we can parse
multiple patches we also need to ensure the final list of sections is
unique so we don't repeat ourselves.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 scripts/get_maintainer.py | 47 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/scripts/get_maintainer.py b/scripts/get_maintainer.py
index bf45865438e..daeefecef64 100755
--- a/scripts/get_maintainer.py
+++ b/scripts/get_maintainer.py
@@ -15,6 +15,7 @@
 from pathlib import Path
 from enum import StrEnum, auto
 from re import compile as re_compile
+from re import sub as re_sub
 
 #
 # Subsystem MAINTAINER entries
@@ -187,6 +188,29 @@ def read_maintainers(src):
 
     return entries
 
+#
+# Helper functions for dealing with patch files
+#
+patchfile_re = re_compile(r"\+\+\+\s+(\S+)")
+
+#TODO: also return a list of keyword hits for K:?
+def extract_filenames_from_patch(patchfile):
+    """
+    Read a patchfile and return a list of files which are modified by
+    the patch.
+    """
+    file_list = []
+
+    with open(patchfile, 'r', encoding='utf-8') as f:
+        for line in f:
+            m = patchfile_re.match(line)
+            if m:
+                # strip leading [ab]/
+                stripped = re_sub(r'^[^/]*/', '', m.group(1))
+                as_path = Path(path.abspath(stripped))
+                file_list.append(as_path)
+
+    return file_list
 
 #
 # Helper functions for dealing with the source path
@@ -305,14 +329,27 @@ def main():
         print(f"loaded {len(maint_sections)} from MAINTAINERS")
         exit(0)
 
-    relevent_maintainers = None
+    # Build array of Path objects representing the files
+    files = []
 
     if args.file:
-        relevent_maintainers = [ms for ms in maint_sections if
-                                ms.is_file_covered(args.file)]
+        files.append(args.file)
+
+    if args.patch:
+        for p in args.patch:
+            pfiles = extract_filenames_from_patch(p)
+            files.extend(pfiles)
+
+    # unique set of maintainer sections
+    maintained: set[MaintainerSection] = set()
+
+    for f in files:
+        fmaint = [ms for ms in maint_sections if ms.is_file_covered(f)]
+        for m in fmaint:
+            maintained.add(m)
 
-    for rm in relevent_maintainers:
-        print(rm)
+    for rm in maintained:
+        print(str(rm))
 
 
 if __name__ == '__main__':
-- 
2.47.3